1. Field of the Invention
The present invention relates to a field communication apparatus including communication units that perform communication between field devices and a host device. In particular, the present invention relates to an explosion-proof field communication apparatus.
Priority is claimed on Japanese Patent Application No. 2011-013041, filed Jan. 25, 2011, the content of which is incorporated herein by reference.
2. Description of the Related Art
All patents, patent applications, patent publications, scientific articles, and the like, which will hereinafter be cited or identified in the present application, will hereby be incorporated by reference in their entirety in order to describe more fully the state of the art to which the present invention pertains.
In a process control system used, for example, at an oil plant, a remote input/output device (remote IO) including a communication unit for connection with a field device and a host device may be used. Since the remote input/output device is placed at a site of the plant, the remote input/output device is installed while being accommodated in an explosion-proof box.
Japanese Unexamined Patent Application, First Publication No. 2009-38545 discloses an explosion-proof repeater in which a communication unit is accommodated in a housing having a pressure-resistant and explosion-proof structure.
In a conventional system, when maintenance of a remote input/output device is required due to, for example, failure, operation of a plant needs to stop or hazardous atmosphere needs to be eliminated, and an explosion-proof box needs to be opened to perform maintenance work. Therefore, the plant operation cannot continue during maintenance and a loss is generated during the operation.